Wireless communications system and wireless radio frequency apparatus

ABSTRACT

A wireless communications system includes a BBU, an optical multiplexer, M (greater than or equal to 2) first optical transceivers, and a wireless radio frequency apparatus, where the M first optical transceivers are provided between the BBU and the optical multiplexer, operating wavelengths of the M first optical transceivers are different from each other. The wireless radio frequency apparatus includes M RRUs, M second optical transceivers separately corresponding to the M first optical transceivers, and at least one optical splitter, where the M second optical transceivers are separately connected to the M RRUs, and an operating wavelength of a first optical transceiver matches an operating wavelength of a corresponding second optical transceiver. The M second optical transceivers are connected to a same optical fiber by the at least one optical splitter, and the optical fiber is connected to the optical multiplexer and one of the at least one optical splitter.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of international patent applicationnumber PCT/CN2014/076503 filed on Apr. 29, 2014, which is incorporatedby reference.

TECHNICAL FIELD

The present application relates to the field of communicationstechnologies, and in particular, to a wireless communications system anda wireless radio frequency apparatus.

BACKGROUND

Many radio networks use a distributed base station architecture, where aremote radio unit (RRU) is connected to a baseband processing unit (BBU)by an optical fiber, and one BBU can support multiple RRUs. In ascenario in which multiple RRUs need to be connected to a same BBU at asame station, cascading of the multiple RRUs is a common networkingmanner.

In the following, a data transmission mode of a wireless communicationssystem 900 in which one BBU supports two cascaded RRUs is used as anexample for description. As shown in FIG. 5, in a downlink direction, aBBU 90 receives downlink data sent by a gateway, processes the downlinkdata, and sends processed downlink data to an optical transceiver 93through a common public radio interface (CPRI), where the opticaltransceiver is also referred to as an optical module. The opticaltransceiver 93 converts the processed downlink data into a firstdownlink optical carrier signal, and sends, through an optical fiber,the first downlink optical carrier signal to an optical transceiver 94that corresponds to an RRU 91. The optical transceiver 94 converts thefirst downlink optical carrier signal into a first downlink electricalsignal, and sends the first downlink electrical signal to the RRU 91.The RRU 91 selectively receives part of the first downlink electricalsignal, sends the remaining signal to an optical transceiver 95. Theoptical transceiver 95 converts the remaining signal into a seconddownlink optical carrier signal, and sends the second downlink opticalcarrier signal to an optical transceiver 96 through an optical fiber.The optical transceiver 96 converts the second downlink optical carriersignal into a second downlink electrical signal, and sends the seconddownlink electrical signal to an RRU 92. In this way, the downlink datareceived from the gateway can be sent to a mobile terminal using the RRU91 and the RRU 92.

In an uplink direction, the RRU 91 and the RRU 92 separately receiveuplink data sent by the mobile terminal, and process the uplink data toobtain an uplink electrical signal. The RRU 92 sends an obtained firstuplink electrical signal to the optical transceiver 96 that correspondsto the RRU 92. The optical transceiver 96 converts the first uplinkelectrical signal into a first uplink optical carrier signal, and sends,through an optical fiber, the first uplink optical carrier signal to theoptical transceiver 95 that corresponds to the RRU 91. The opticaltransceiver 95 converts the first uplink optical carrier signal into asecond uplink electrical signal, and sends the second uplink electricalsignal to the RRU 91. The RRU 91 integrates the second uplink electricalsignal with the uplink electrical signal obtained by the RRU 91 toobtain a third uplink electrical signal, and sends the third uplinkelectrical signal to the optical transceiver 94 connected to the RRU 91.The optical transceiver 94 converts the third uplink electrical signalinto a second uplink optical carrier signal, and sends the second uplinkoptical carrier signal to the BBU 90 through an optical fiber such thatthe BBU 90 processes the second uplink optical carrier signal and sendsa processed second uplink optical carrier signal to the gateway.

It can be seen that the RRU 91 needs to forward data sent to or from theRRU 92, and when the RRU 91 is faulty, the RRU 92 cannot work.

Therefore, the existing networking structure of a distributed basestation has the following disadvantages where when an RRU (referred toas a current RRU) of cascaded RRUs is faulty, a next RRU cannot work,which reduces system reliability.

SUMMARY

In view of this, embodiments of the present application provide awireless communications system and a wireless radio frequency apparatus,which resolve a technical problem of low system reliability caused bythat when an RRU of multiple cascaded RRU is faulty in an existingdistributed base station architecture, a next RRU cannot work.

A first aspect provides a wireless radio frequency apparatus, where thewireless radio frequency apparatus includes M RRUs, M opticaltransceivers, and at least one optical splitter, where M is an integergreater than or equal to 2. The M optical transceivers are separatelyconnected to the M RRUs, and operating wavelengths of the M opticaltransceivers are different from each other, and the M opticaltransceivers are connected to a same optical fiber by the at least oneoptical splitter.

In a first possible implementation manner of the first aspect, theoptical splitter is a 1:N optical splitter, and N is an integer greaterthan or equal to 2 and less than or equal to M.

With reference to the first possible implementation manner of the firstaspect, in a second possible implementation manner of the first aspect,the optical splitter is a 1:2 optical splitter, and a quantity ofoptical splitters is M−1.

With reference to the second possible implementation manner of the firstaspect, in a third possible implementation manner of the first aspect,when M is greater than 2, the M−1 optical splitters are connected toeach other by a single-core optical fiber.

With reference to the first aspect or any one of the first to thirdpossible implementation manners of the first aspect, in a fourthpossible implementation manner of the first aspect, the optical fiber isa single-core optical fiber.

With reference to the first aspect or any one of the first to fourthpossible implementation manners of the first aspect, in a fifth possibleimplementation manner of the first aspect, an operating wavelength ofeach optical transceiver of the first optical transceivers and thesecond optical transceivers includes a receive wavelength and a transmitwavelength.

A second aspect of this application provides a wireless communicationssystem, where the wireless communications system includes a BBU, anoptical multiplexer, M first optical transceivers, and a wireless radiofrequency apparatus, where the M first optical transceivers are providedbetween the BBU and the optical multiplexer, operating wavelengths ofthe M first optical transceivers are different from each other, and M isan integer greater than or equal to 2. The wireless radio frequencyapparatus includes M RRUs, M second optical transceivers, and at leastone optical splitter, where the M second optical transceivers areseparately connected to the M RRUs, and are separately corresponding tothe M first optical transceivers, and an operating wavelength of a firstoptical transceiver matches an operating wavelength of a second opticaltransceiver corresponding to the first optical transceiver. The M secondoptical transceivers are connected to a same optical fiber by the atleast one optical splitter, and the optical fiber is connected to theoptical multiplexer and one of the at least one optical splitter.

In a first possible implementation manner of the second aspect, theoptical splitter is a 1:N optical splitter, and N is an integer greaterthan or equal to 2 and less than or equal to M.

With reference to the first possible implementation manner of the secondaspect, in a second possible implementation manner of the second aspect,the optical splitter is a 1:2 optical splitter, and a quantity ofoptical splitters is M−1.

With reference to the second possible implementation manner of thesecond aspect, in a third possible implementation manner of the secondaspect, the M−1 optical splitters are connected to each other by asingle-core optical fiber when M is greater than 2.

With reference to the second aspect or the first, the second, or thethird possible implementation manner of the second aspect, in a fourthpossible implementation manner of the second aspect, the optical fiberis a single-core optical fiber.

With reference to the second aspect or any one of the first to fourthpossible implementation manners of the second aspect, in a fifthpossible implementation manner of the second aspect, an operatingwavelength of each optical transceiver of the first optical transceiversand the second optical transceivers includes a receive wavelength and atransmit wavelength.

With reference to the fifth possible implementation manner of the secondaspect, in a sixth possible implementation manner of the second aspect,that an operating wavelength of a first optical transceiver matches anoperating wavelength of a second optical transceiver corresponding tothe first optical transceiver includes that in the first opticaltransceiver and the second optical transceiver corresponding to thefirst optical transceiver, the transmit wavelength of the first opticaltransceiver is the same as the receive wavelength of the second opticaltransceiver, and the receive wavelength of the first optical transceiveris the same as the transmit wavelength of the second opticaltransceiver.

In the wireless communications system of this application, opticalsignals of different RRUs are transmitted using different wavelengths(which includes transmission from an RRU to a BBU, and transmission froma BBU to an RRU), and correspondingly, optical transceivers of thecascaded RRUs work at different wavelengths. Further, an opticalsplitter is further provided, and the optical transceivers of thesecascaded RRUs are all connected to the optical splitter, and areconnected to a same optical fiber by the optical splitter. In this way,optical signals of multiple RRUs that are transmitted on the opticalfiber can be transmitted to the optical transceivers of all the RRUsusing the optical splitter, and each optical transceiver receives only asignal corresponding to its own operating wavelength. Therefore, eachRRU can correctly receive its own signal, and when an RRU is faulty,operation of the other RRUs is not affected, which greatly increasessystem reliability, and resolves the technical problem of low systemreliability caused by that when a RRU of multiple cascaded RRUs isfaulty in an existing distributed base station architecture, all nextRRUs cannot work.

In addition, after the foregoing solution is used, each RRU receives itsown signal without the need to forward a signal of another RRU, whichreduces a requirement on bandwidth of a CPRI and reduces costs, and doesnot cause any limitation to a quantity of levels of cascaded RRUs.Further, each RRU no longer needs to be provided with two CPR's, therebyfurther reducing the costs. In addition, a decrease in the requirementon the bandwidth of the CPRI further reduces a requirement on a rate ofan optical transceiver, which further reduces the costs.

BRIEF DESCRIPTION OF DRAWINGS

To describe the technical solutions in the embodiments of the presentapplication more clearly, the following briefly introduces theaccompanying drawings required for describing the embodiments. Theaccompanying drawings in the following description show merely someembodiments of the present application.

FIG. 1 is a schematic structural diagram of a wireless communicationssystem according to an embodiment of the present application;

FIG. 2 is a schematic structural diagram of a wireless communicationssystem according to another embodiment of the present application;

FIG. 3 is a schematic structural diagram of a wireless communicationssystem according to still another embodiment of the present application;

FIG. 4 is a schematic structural diagram of a wireless communicationssystem according to yet another embodiment of the present application;and

FIG. 5 is a schematic structural diagram of a wireless communicationssystem.

DESCRIPTION OF EMBODIMENTS

At present, in a distributed base station architecture, cascading ofmultiple RRUs is a common networking manner. However, for thisnetworking manner, a current RRU sends data to a next RRU in aforwarding manner, and all next RRUs cannot work when the current RRU isfaulty, which results in reduced system reliability.

In this application, based on a full consideration of this problem,optical signals of different RRUs are transmitted using differentwavelengths (which includes transmission from an RRU to a BBU, andtransmission from a BBU to an RRU), and correspondingly, opticaltransceivers of the cascaded RRUs work at different wavelengths.Further, an optical splitter is further provided, and the opticaltransceivers of these cascaded RRUs are all connected to the opticalsplitter, and are connected to a same optical fiber by the opticalsplitter. In this way, optical signals of multiple RRUs that aretransmitted on the optical fiber can be transmitted to the opticaltransceivers of all the RRUs using the optical splitter, and eachoptical transceiver receives only a signal corresponding to its ownoperating wavelength. Therefore, each RRU can correctly receive its ownsignal, and working of the other RRUs is not affected when an RRU isfaulty, which greatly increases system reliability.

In addition, in some other works, data of all RRUs needs to pass througha CPRI of the first RRU, and therefore, there is a relatively highrequirement on bandwidth of the CPRI, which increases costs. In a casein which the bandwidth of the CPRI is limited, a quantity of levels ofcascaded RRUs is limited. In addition, an increase in the bandwidth ofthe CPRI increases a requirement on a rate of an optical transceiver,which further increases the costs.

However, after the foregoing solution is used, each RRU receives its ownsignal without the need to forward a signal of another RRU, whichreduces the requirement on the bandwidth of the CPRI and reduces thecosts, and does not cause any limitation to the quantity of levels ofcascaded RRUs. Further, each RRU no longer needs to be provided with twoCPRI, thereby further reducing the costs. In addition, a decrease in therequirement on the bandwidth of the CPRI further reduces the requirementon the rate of the optical transceiver, which further reduces the costs.

It can be seen that the technical solution of this application not onlyresolves the problem of low reliability in other approaches, but alsogreatly reduces costs, and does not cause any limitation to a quantityof levels of cascaded RRUs.

To make persons skilled in the art better understand the solution of thepresent application, the following clearly describes the technicalsolution in the embodiments of the present application with reference tothe accompanying drawings in the embodiments of the present application.The described embodiments are merely some rather than all of theembodiments of the present application.

Embodiment 1

FIG. 1 is a schematic structural diagram of a wireless communicationssystem 100 according to an embodiment of the present application. Asshown in FIG. 1, the wireless communications system 100 includes a BBU10, an optical multiplexer 20, optical transceivers 31 and 32, and awireless radio frequency apparatus 500, where the wireless radiofrequency apparatus 500 includes RRUs 41 and 42, optical transceivers 51and 52, and an optical splitter 60.

The BBU 10 may include a transmission subsystem, a baseband subsystem, acontrol subsystem, and a power supply module. The transmission subsystemis configured to implement a function of transmitting and receivingdata, and includes an interface between the BBU 10 and a corenetwork/controller and an interface between the BBU 10 and a radiofrequency module, where the interface between the BBU 10 and the radiofrequency module may be a CPRI or an Open Base Station ArchitectureInitiative (OBSAI) interface. In this implementation manner, the BBU 10includes two interfaces, that is, a quantity of interfaces is the sameas a quantity of RRUs 41 and 42. The power supply module is configuredto provide required power supply for the BBU 10.

The baseband subsystem is mainly configured to implement a basebandprocessing function for uplink and downlink data, and mainly includes anuplink processing module and a downlink processing module. The uplinkprocessing module is configured to demodulate and decode uplink basebanddata from the transmission subsystem, and transmit decoded anddemodulated data through the transmission subsystem. The downlinkprocessing module is configured to modulate and encode downlink basebanddata from the transmission subsystem, and transmit modulated and encodeddata through the transmission subsystem.

The control subsystem is configured to manage the entire wirelesscommunications system 100, and the control subsystem may have, forexample, one or more of the functions, operation and maintenancefunctions such as device management, configuration management, alarmmanagement, software management, and debugging and testing management, asignaling processing function such as logical resource management, clockmodule functions such as phase locking a global positioning system (GPS)clock, performing frequency dividing, phase locking and phaseadjustment, and providing a clock, which meets a requirement, for anentire base station.

The RRUs 41 and 42 are configured to send, to an antenna feeder and bymeans of transmission filtering, a downlink baseband signal that isreceived from the BBU 10 and has undergone frequency conversion,filtering, radio frequency filtering, and passed a linear poweramplifier, or perform filtering, low noise amplification, further radiofrequency small signal amplification and filtering, down-conversion,analog-to-digital conversion, digital intermediate frequency processing,and the like on an uplink signal received from a mobile terminal. EachRRU 41 and 42 is communicatively connected to the BBU 10 using oneinterface.

The optical multiplexer 20 is referred to as an optical MUX for short,with a full name being optical multiplexer. The optical multiplexer 20is a device that combines and separates several optical carrier signalshaving different wavelengths, and may combine several optical carriersignals having different wavelengths onto one optical fiber fortransmission, or separate optical carrier signals into multiple opticalcarrier signals according to the wavelengths to transmit the multipleoptical carrier signals through multiple optical fibers. The opticalmultiplexer 20 generally includes multiple input interfaces and oneoutput interface. In this implementation manner, the optical multiplexer20 includes two input interfaces and one output interface, where boththe input interfaces and the output interface are single-corebidirectional interfaces. In another implementation manner, theinterfaces may be dual-core bidirectional interfaces.

The optical transceiver, such as the optical transceivers 31, 32, 51,and 52 is also referred to as an optical module, and is configured toimplement optical/electrical conversion, where the optical/electricalconversion mentioned herein includes conversion from an optical signalto an electrical signal, and also includes conversion from an electricalsignal to an optical signal. The optical transceivers 31 and 32 areprovided between the BBU 10 and the optical multiplexer 20, where theoptical transceiver 31 is connected to one input interface of theoptical multiplexer 20 and one CPRI of the BBU 10, and the opticaltransceiver 32 is connected to another input interface of the opticalmultiplexer 20 and another CPRI of the BBU 10. The optical transceivers51 and 52 are connected to the RRUs 41 and 42, respectively, that is,the optical transceiver 51 is connected to the RRU 41, and the opticaltransceiver 52 is connected to the RRU 42.

An optical transceiver generally includes an optoelectronic device, afunctional circuit, an optical interface, and the like, where theoptoelectronic device includes an emitting part and a receiving part.The emitting part is implemented as follows. After an electrical signalwith a particular bit rate is input and processed by an internal driverchip, a semiconductor laser device (LD) or a light-emitting diode (LED)is driven to emit a modulated optical signal having a correspondingrate, where an automatic optical power control circuit is providedinside the optoelectronic device in order to keep power of the outputoptical signal steady. The receiving part is implemented as follows.After an optical signal with a particular bit rate is input into themodule, the optical signal is converted into an electrical signal by aphotodetection diode, and a head amplifier amplifies the electricalsignal and outputs an electrical signal with a corresponding bit rate.In short, a function of the optical transceiver is optical/electricalconversion.

Each optical transceiver connected to the BBU 10 is corresponding to oneRRU, and at each RRU, one optical transceiver corresponding to the RRUis provided. Operating wavelengths of optical transceivers correspondingto a same RRU match each other, and operating wavelengths of opticaltransceivers corresponding to different RRUs are different, for example,operating wavelengths of the optical transceivers 31 and 51corresponding to the RRU 41 match each other, and operating wavelengthsof the optical transceivers 32 and 52 corresponding to the RRU 42 matcheach other, but the operating wavelengths of the optical transceivers 31and 32 are different, and the operating wavelengths of the opticaltransceivers 51 and 52 are different, thereby ensuring that the opticaltransceiver corresponding to each RRU receives only a signalcorresponding to its own operating wavelength. That operatingwavelengths match each other mentioned herein refers to that a transmitwavelength of one optical transceiver is the same as a receivewavelength of another optical transceiver such that the other opticaltransceiver can receive an optical signal sent by the opticaltransceiver. For example, a transmit wavelength of the opticaltransceiver 31 is equal to a receive wavelength of the opticaltransceiver 51, and a receive wavelength of the optical transceiver 31is equal to a transmit wavelength of the optical transceiver 51. Atransmit wavelength of the optical transceiver 32 is equal to a receivewavelength of the optical transceiver 52, and a receive wavelength ofthe optical transceiver 32 is equal to a transmit wavelength of theoptical transceiver 52.

In addition, the foregoing optical transceivers may be dual-corebidirectional optical transceivers, or may be single-core bidirectionaloptical transceivers. When the optical transceivers are dual-corebidirectional optical transceivers, each optical transceiver has oneoperating wavelength, which is not only used for transmission, but alsoused for reception. When the optical transceivers are single-corebidirectional optical transceivers, each optical transceiver has twooperating wavelengths, including a transmit wavelength and a receivewavelength. In this implementation manner, by way of example, theoptical transceivers are single-core bidirectional optical transceivers,that is, transmission and reception are combined to be performed on oneoptical fiber, where different wavelengths are used to transmit andreceive optical signals.

For example, the transmit wavelength of the optical transceiver 31 isλ1, and the receive wavelength of the optical transceiver 31 is λ2,where λ2 is unequal to λ1. The transmit wavelength of the opticaltransceiver 32 is λ3, and the receive wavelength of the opticaltransceiver 32 is λ4, where λ4 is unequal to λ3. Further, the transmitwavelength λ1 of the optical transceiver 31 is different from thetransmit wavelength λ3 of the optical transceiver 32, and the receivewavelength λ2 of the optical transceiver 31 is different from thereceive wavelength λ1 of the optical transceiver 32 in order to ensurethat optical signals sent out by different optical transceivers can bereceived by different RRUs. In addition, because the foregoing opticaltransceivers are single-core bidirectional optical transceivers, thetransmit wavelength λ1 and the receive wavelength λ2 of the opticaltransceiver 31 are different, and the transmit wavelength λ3 and thereceive wavelength λ1 of the optical transceiver 32 are different.Therefore, λ1, λ2, λ3, and λ4 are different from each other.

The optical transceiver 51 and the optical transceiver 31 are used in apaired manner, and the optical transceiver 52 and the opticaltransceiver 32 are used in a paired manner. Therefore, the receivewavelength of the optical transceiver 51 is λ1, and the transmitwavelength of the optical transceiver 51 is λ2 when the transmitwavelength of the optical transceiver 31 is λ1, and the receivewavelength of the optical transceiver 31 is λ2. The receive wavelengthof the optical transceiver 52 is λ3, and the transmit wavelength of theoptical transceiver 52 is λ4 when the transmit wavelength of the opticaltransceiver 32 is λ3, and the receive wavelength of the opticaltransceiver 32 is λ1, where λ1, λ2, λ3, and λ4 are different from eachother.

The optical transceivers 51 and 52 are connected, by the opticalsplitter 60, to an optical fiber 70 that is connected to the opticalmultiplexer 20. Further, the optical transceivers 51 and 52 may beconnected to the optical splitter 60 using an optical fiber, forexample, a single-core bidirectional optical fiber. The opticalmultiplexer 20 may be also connected to the optical splitter 60 using anoptical fiber, for example, a single-core bidirectional optical fiber.Compared with using a dual-core bidirectional optical fiber, using thesingle-core bidirectional optical fiber reduces costs.

The optical splitter 60 is also referred to as an optical splittingdevice, is one of important passive devices on an optical fiber link,and is configured to perform coupling, splitting, and distribution of anoptical signal. Quantities of input and output interfaces of the opticalsplitter 60 may be selected according to a need. As shown in FIG. 1, inthis implementation manner, a quantity of RRUs is two, a quantity ofoptical splitters 60 is one, and a quantity of optical multiplexers 20is one, and in this case, the optical splitter 60 is a 1:2 opticalsplitter. Alternatively, as shown in FIG. 3 or FIG. 4, when multipleRRUs are connected in a cascaded manner, that is, each RRU is connectedto the optical splitter 60 by one optical transceiver, and the opticalsplitter 60 is also a 1:2 optical splitter. Because the 1:2 opticalsplitter has a small volume and can be directly placed in a maintenancecavity of the RRU, costs of mounting are reduced.

In this implementation manner, the quantity of RRUs is two, a quantityof interfaces of BBUs 10 is also two, a quantity of optical transceiversconnected to the BBUs 10 is also two, and one optical transceiver isprovided between each RRU and the optical splitter. In a specificimplementation manner, the BBU 10 and the optical multiplexer 20 may beplaced in an equipment room, and the RRUs 41 and 42 may be remotelyplaced at an outdoor station using an optical fiber. The opticaltransceiver 31 is mounted on an interface 11, corresponding to the RRU41, of the BBU 10, and the optical transceiver 32 is mounted on aninterface 12, corresponding to the RRU 42, of the BBU 10. The opticaltransceiver 51 is mounted on the RRU 41, and the optical transceiver 52is mounted on the RRU 42. The optical splitter 60 may be independentlyprovided, or may be provided in a maintenance cavity of the RRU 41.

In a downlink direction, the BBU 10 modulates and encodes downlinkbaseband data, and sends modulated and encoded downlink data to theoptical transceivers 31 and 32 through the interface 11 and theinterface 12. The optical transceivers 31 and 32 convert the receiveddownlink data into optical carrier signals having different wavelengths,and send the optical carrier signals to the optical multiplexer 20, andthe optical multiplexer 20 combines the optical carrier signals from theoptical transceivers 31 and 32 onto one optical fiber in order to sendthe optical carrier signals to the optical splitter 60 though theoptical fiber 70. The optical transceivers 51 and 52 connected to theoptical splitter 60 selectively receive, according to the wavelengths,data corresponding to the wavelengths. The receive wavelength of theoptical transceiver 51 is equal to the transmit wavelength of theoptical transceiver 31, and the optical transceiver 51 can receive onlydata sent by the optical transceiver 31 to the optical multiplexer 20.The receive wavelength of the optical transceiver 52 is equal to thetransmit wavelength of the optical transceiver 32, and the opticaltransceiver 52 can receive only data sent by the optical transceiver 32to the optical multiplexer 20. After converting received signals intodownlink electrical signals, the two optical transceivers 51 and 52 sendthe downlink electrical signals to the RRUs 41 and 42, respectively, andthe RRUs 41 and 42 transmit the received signals to an antenna feeder bymeans of transmission filtering after the received signals undergoesradio frequency filtering and passes a linear power amplifier.

In an uplink direction, the RRUs 41 and 42 perform filtering, low noiseamplification, further radio frequency small signal amplification andfiltering, down-conversion, analog-to-digital conversion, digitalintermediate frequency processing, and the like on an uplink signalreceived from a mobile terminal to generate uplink electrical signals,and transmit the uplink electrical signals to the optical transceivers51 and 52, respectively. The optical transceivers 51 and 52 convert thereceived uplink electrical signals into uplink optical carrier signals.The optical transceivers 51 and 52 have different transmit wavelengths,where a transmit wavelength of the optical transceiver 51 is equal tothe receive wavelength of the optical transceiver 31 such that data sentby the optical transceiver 51 can be only received by the opticaltransceiver 31, and a transmit wavelength of the optical transceiver 52is equal to the receive wavelength of the optical transceiver 32 suchthat data sent by the optical transceiver 52 can be only received by theoptical transceiver 32. The optical splitter 60 couples the received twolinks of uplink optical carrier signals onto a same downlink opticalfiber 70, and sends the signals to the optical multiplexer 20. Theoptical multiplexer 20 separates the received optical carrier signals,and separately sends the separated optical carrier signals to theoptical transceivers 31 and 32. The optical transceivers 31 and 32convert the received optical carrier signals into uplink data signals,and send the uplink data signals to corresponding interfaces of the BBU10, and the BBU 10 demodulates and decodes the received uplink datasignals, and transmits demodulated and decoded uplink data signals to agateway.

It can be seen that when the RRU 41 is faulty, a signal of the RRU 42can be directly transmitted to the optical splitter 60, and transferredto the BBU 10 using the optical splitter 60, and a signal of the BBU 10can also be transmitted to the RRU 42 using the optical splitter 60,thereby ensuring that the RRU 42 can work normally.

In the foregoing wireless communications system 100, an optical splitter60 is provided between two RRUs, that is, a first RRU 41 and a secondRRU 42, and even when the first RRU 41 is faulty, a signal of the secondRRU 42 can be directly transmitted to the optical splitter 60, andtransferred to a BBU 10 using the optical splitter 60, and a signal ofthe BBU 10 can also be transmitted to the second RRU 42 using theoptical splitter 60, thereby ensuring that the RRU 42 can work normally,which resolves a technical problem of low system reliability caused bythat when a RRU of multiple cascaded RRUs is faulty in an existingdistributed base station architecture, all next RRUs cannot work.

In addition, all links use different wavelengths for communication, andare completely independent of each other, which also resolves atechnical problem that when multiple RRUs are cascaded, a rate of anoptical transceiver increases and a quantity of cascaded RRUs on a samelink is limited because communication bandwidth is superimposed.

Embodiment 2

Base on a same inventive idea, this application further provides awireless communications system 200. As shown in FIG. 2, the wirelesscommunications system 200 is different from the wireless communicationssystem 100 in that a quantity of optical transceivers and a quantity ofRRUs are different, and an optical splitter is different.

In this implementation manner, a quantity of RRUs 40 is M,correspondingly, M optical transceivers 50 are separately connected tothe M RRUs 40, and M optical transceivers 30 are provided on Minterfaces between a BBU 10 and the M RRUs 40. An optical splitter 60may be a 1:N optical splitter, where M is an integer greater than orequal to 3, and N is an integer greater than or equal to 2. The M RRUs40 are separately connected to the optical splitter 60 by the M opticaltransceivers 50.

In this implementation manner, N is equal to M, the optical splitter 60is a 1:M optical splitter and has M+1 interfaces, where a quantity ofoptical splitters is one. In this case, all the RRUs 40 are connectedthe optical splitter 60.

In another implementation manner, N may be unequal to M, for example,when N is equal to 2, the optical splitter 60 is a 1:2 optical splitterand has three interfaces, where a quantity of optical splitters is M−1.One interface of a first optical splitter is connected to an opticalmultiplexer 20 by an optical fiber, such as an optical fiber 70 in orderto receive multiple links of optical signals that are obtained by theoptical multiplexer 20 by means of combining, and the other twointerfaces are separately connected to the first RRU 40 and the secondoptical splitter. One interface of the ith optical splitter is connectedto the (i−1)th optical splitter, and the other two interfaces areseparately connected to the ith RRU and the (i+1)th optical splitter,where 2≤i≤M−2. One interface of the last optical splitter, that is, the(M−1)th optical splitter, is connected to the (M−2)th optical splitter,and the other two interfaces are separately connected to the (M−1)th RRUand the Mth RRU.

The operating principle of the foregoing wireless communications system200 is the same as that of the wireless communications system 100, andthe details are not described herein again. When any RRU 40 of the MRRUs 40 is faulty, signals of the other RRUs 40 can be directlytransmitted to the optical splitter 60, and transferred to the BBU 10using the optical splitter 60, and a signal of the BBU 10 can also betransmitted to the other RRUs 40 using the optical splitter 60, therebyensuring that the other RRUs 40 can work normally, which resolves atechnical problem of low system reliability caused by that when an RRUof multiple cascaded RRUs is faulty in an existing distributed basestation architecture, all next RRUs cannot work.

In addition, all links use different wavelengths for communication, andare completely independent of each other, which also resolves atechnical problem that when multiple RRUs are cascaded, a rate of anoptical transceiver increases and a quantity of cascaded RRUs on a samelink is limited because communication bandwidth is superimposed.

Embodiment 3

Base on a same inventive idea, this application further provides awireless communications system 300. As shown in FIG. 3, FIG. 3 is aschematic structural diagram of a wireless communications system 300according to another embodiment of the present application. The wirelesscommunications system 300 is different from the wireless communicationssystem 100 in FIG. 1 in that a quantity of optical splitters is two(designated as optical splitters 61 and 62), and a quantity of RRUs isthree (designated as RRUs 41, 42, and 43), and correspondingly, aquantity of interfaces of a BBU 10 is also three, a quantity of opticaltransceivers connected to the BBU 10 is three (designated as opticaltransceivers 31, 32, and 33), and a quantity of optical transceiversconnected to the RRUs 40 is also three (designated as opticaltransceivers 51, 52, and 53).

The quantity of optical splitters 61 and 62 is one less than thequantity of RRUs 41, 42, and 43, that is, there are two opticalsplitters 61 and 62. The optical splitter 61 is connected to an opticalmultiplexer 20 and the optical splitter 62, an RRU 41 is connected tothe optical splitter 61 by an optical transceiver 51, an RRU 42 isconnected to the optical splitter 62 by an optical transceiver 52, andan RRU 43 is connected to the optical splitter 62 by an opticaltransceiver 53.

In a specific implementation manner, the BBU 10 and the opticalmultiplexer 20 are placed in an equipment room, and the three RRUs 31,32, and 33 may be remotely placed at an outdoor station using an opticalfiber. An optical transceiver 31 is mounted on an interface 11,corresponding to the first RRU 41, of the BBU 10. An optical transceiver32 is mounted on an interface 12, corresponding to the second RRU 42, ofthe BBU 10. An optical transceiver 33 is mounted on an interface 13,corresponding to the third RRU 43, of the BBU 10. The opticaltransceiver 51 is mounted on the RRU 41, the optical transceiver 52 ismounted on the RRU 42, and the optical transceiver 53 is mounted on theRRU 43. The optical splitter 61 is placed in a maintenance cavity of theRRU 41, and the optical splitter 62 is placed in a maintenance cavity ofthe RRU 42.

In a downlink direction, the BBU 10 modulates and encodes downlinkbaseband data, and sends modulated and encoded downlink data to theoptical transceivers 31, 32 and 33 through the interface 11, theinterface 12, and the interface 13. The optical transceivers 31, 32 and33 convert the received downlink data into optical carrier signalshaving different wavelengths, and send the optical carrier signals tothe optical multiplexer 20, and the optical multiplexer 20 combines thereceived optical carrier signals onto one optical fiber 70, and sendsthe optical carrier signals to the three optical transceivers 51, 52,and 53 through the optical splitters 61 and 62, and the three opticaltransceivers 51, 52, and 53 selectively receive, according to thewavelengths, data corresponding to the wavelengths. A receive wavelengthof the optical transceiver 51 is equal to a transmit wavelength of theoptical transceiver 31, and the optical transceiver 51 can receive onlydata sent by the optical transceiver 31. A receive wavelength of theoptical transceiver 52 is equal to a transmit wavelength of the opticaltransceiver 32, and the optical transceiver 52 can receive only datasent by the optical transceiver 32. A receive wavelength of the opticaltransceiver 53 is equal to a transmit wavelength of the opticaltransceiver 33, and the optical transceiver 53 can receive only datasent by the optical transceiver 33. After converting the receivedsignals into downlink electrical signals, the three optical transceivers51, 52, and 53 send the downlink electrical signals to the three RRUs41, 42, and 43, and the three RRUs 41, 42, and 43 sends the receivedsignals to an antenna feeder by means of transmission filtering afterthe signals undergoes radio frequency filtering and passes a linearpower amplifier.

In an uplink direction, the three RRUs 41, 42, and 43 perform filtering,low noise amplification, further radio frequency small signalamplification and filtering, down-conversion, analog-to-digitalconversion, digital intermediate frequency processing, and the like onan uplink signal received from a mobile terminal to generate uplinkelectrical signals, and transmit the uplink electrical signals to thethree optical transceivers 51, 52, and 53, and the three opticaltransceivers 51, 52, and 53 convert the received uplink electricalsignals into uplink optical carrier signals. The three opticaltransceivers 51, 52, and 53 have different transmit wavelengths, where atransmit wavelength of the optical transceiver 51 is equal to a receivewavelength of the optical transceiver 31, and data sent by the opticaltransceiver 51 can be only received by the optical transceiver 31. Atransmit wavelength of the optical transceiver 52 is equal to a receivewavelength of the optical transceiver 32, and data sent by the opticaltransceiver 52 can be only received by the optical transceiver 32, and atransmit wavelength of the optical transceiver 53 is equal to a receivewavelength of the optical transceiver 33, and data sent by the opticaltransceiver 53 can be only received by the optical transceiver 33. Theoptical splitters 61 and 62 couple the three links of uplink opticalcarrier signals onto a same downlink optical fiber 70, and send thesignals to the optical multiplexer 20. The optical multiplexer 20separates the received optical carrier signals, and separately sends theseparated optical carrier signals to the optical transceivers 31 32, and33. After separately converting the received optical carrier signalsinto uplink data signals, the optical transceivers 31, 32, and 33 sendthe uplink data signals to the corresponding three interfaces 11, 12,and 13 of the BBU 10, respectively, and the BBU 10 demodulates anddecodes the received uplink data signals, and transmits demodulated anddecoded uplink data signals to a gateway.

It can be seen that in the foregoing embodiment, optical signals ofdifferent RRUs are transmitted using different wavelengths, andcorrespondingly, optical transceivers of the cascaded RRUs work atdifferent wavelengths. Optical splitters are further provided, and theoptical transceivers of these cascaded RRUs are all connected to theoptical splitters, and are connected to a same optical fiber by theoptical splitters. In this way, the optical signals of the multiple RRUsthat are transmitted on the optical fiber can be transmitted to theoptical transceivers of all the RRUs using the optical splitters, andeach optical transceiver receives only a signal corresponding to its ownoperating wavelength. Therefore, each RRU can correctly receive its ownsignal, and when an RRU is faulty, operation of the other RRUs is notaffected. For example, when the RRU 41 is faulty, signals of the RRUs 42and 43 can be directly transferred to the BBU 10 using the opticalsplitters 61 and 62, and a signal of the BBU 10 can also be transmittedto the RRU 42 and the RRU 43 using the optical splitters 61 and 62,thereby ensuring that the RRUs 42 and 43 can work normally. When boththe RRU 41 and the RRU 42 are faulty, the RRU 43 can transfer a signalto the BBU 10 using the optical splitters 62 and 61, and a signal of theBBU 10 can also be transferred to the RRU 43 using the optical splitters61 and 62, which resolves a technical problem of low system reliabilitycaused by that when an RRU of multiple cascaded RRUs is faulty in anexisting distributed base station architecture, all next RRUs cannotwork.

In addition, all links use different wavelengths for communication, andare completely independent of each other, which also resolves atechnical problem that when multiple RRUs are cascaded, a rate of anoptical transceiver increases and a quantity of cascaded RRUs on a samelink is limited because communication bandwidth is superimposed.

Embodiment 4

Base on a same inventive idea, this application further provides awireless communications system 400. As shown in FIG. 4, FIG. 4 is aschematic structural diagram of a wireless communications system 400according to still another embodiment of the present application. Thewireless communications system 400 is different from the wirelesscommunications system 100 in FIG. 2 in that a quantity of RRUs 40, aquantity of optical splitters 60, and a quantity of optical transceivers50 are different. In this implementation manner, the quantity of RRUs 40is M, where M is greater than 3. Correspondingly, M optical transceivers50 are separately connected to the M RRUs, and M optical transceivers 30are provided on M interfaces between a BBU 10 and the M RRUs 40. Theoptical splitter 60 is a 1:2 optical splitter, and the quantity ofoptical splitters 60 is M−1, where the M−1 optical splitters 60 arecascaded using a single-core optical fiber 70.

One interface of the first optical splitter 60 is connected to anoptical multiplexer 20 by the optical fiber 70 in order to receivemultiple links of optical signals that are obtained by the opticalmultiplexer 20 by means of combining, and the other two interfaces areseparately connected to the first RRU 40 and the second optical splitter60. One interface of the ith optical splitter 60 is connected to the(i−1)th optical splitter 60, and the other two interfaces are separatelyconnected to the ith RRU and the (i+1)th optical splitter 60, where2≤i≤M−2. One interface of the last optical splitter 60, that is, the(M−1)th optical splitter 60, is connected to the (M−2)th opticalsplitter 60, and the other two interfaces are separately connected tothe (M−1)th RRU 40 and the Mth RRU 40.

In a specific implementation manner, the BBU 10 and the opticalmultiplexer 20 may be placed in an equipment room, and the M RRUs 40 maybe remotely placed at an outdoor station using an optical fiber 70. Thefirst optical transceiver 30 is mounted on an interface 1, correspondingto the first RRU 40, of the BBU 10. The jth optical transceiver 30 ismounted on an interface j, corresponding to the jth RRU, of the BBU 10,where 1<j<M. The Mth optical transceiver 30 is mounted on an interfaceM, corresponding to the Mth RRU 40, of the BBU 10. The first opticaltransceiver 50 is mounted on the first RRU 40, the jth opticaltransceiver is mounted on the jth RRU 40, where 1<j<M, and the Mthoptical transceiver 50 is mounted on the Mth RRU 40. In addition, thefirst optical splitter 60 may be placed in a maintenance cavity of thefirst RRU 40, the ith optical splitter 60 may be placed in a maintenancecavity of the ith RRU 40, where 2≤i≤M−2, and the (M−1)th opticalsplitter 60 may be placed in a maintenance cavity of the (M−1)th RRU 40.However, this embodiment is not limited thereto, and the opticalsplitters 60 may be placed independently, or placed in another manner.

In a downlink direction, the BBU 10 modulates and encodes downlinkbaseband data, and sends modulated and encoded downlink data to the Moptical transceivers 30. The M optical transceivers 30 convert thereceived downlink data into optical carrier signals having differentwavelengths, and send the optical carrier signals to the opticalmultiplexer 20. The optical multiplexer 20 combines the received opticalcarrier signals onto one optical fiber, and sends the optical carriersignals to the M optical transceivers 50 through the optical splitters60, and the M optical transceivers 50 selectively receive, according tothe wavelengths, data sent to the M optical transceivers 50. Afterseparately converting the received signals into downlink electricalsignals, the M optical transceivers 50 send the downlink electricalsignals to the M RRUs 40, and the M RRUs 40 separately transmit thereceived signals to an antenna feeder by means of transmission filteringafter the received signals undergoes radio frequency filtering andpasses a linear power amplifier.

In an uplink direction, the M RRUs 40 perform filtering, low noiseamplification, further radio frequency small signal amplification andfiltering, down-conversion, analog-to-digital conversion, digitalintermediate frequency processing, and the like on an uplink signalreceived from a mobile terminal to generate uplink electrical signals,and transmit the uplink electrical signals to the M optical transceivers50 correspondingly, and the M optical transceivers 50 separately convertthe received uplink electrical signals into uplink optical carriersignals and send the uplink optical carrier signals to the opticalsplitters 60.

The M optical transceivers 50 have different transmit wavelengths. Eachoptical transceiver 50 has one optical transceiver 30 matching theoptical transceiver 50, that is, a transmit wavelength of each opticaltransceiver 50 is equal to a receive wavelength of one opticaltransceiver 30, and data sent by the optical transceiver 50 can only bereceived by the optical transceiver. The optical splitters 60 couple Mlinks of uplink optical carrier signals onto a same downlink opticalfiber, and send the signals to the optical multiplexer 20. The opticalmultiplexer 20 separates the received optical carrier signals, and sendsthe separated optical carrier signals separately to the M opticaltransceivers 30. The M optical transceivers 30 convert the receivedoptical carrier signals into uplink data signals, and send the uplinkdata signals to the BBU 10, and the BBU 10 demodulates and decodes thereceived uplink data signals, and transmits demodulated and decodeduplink data signals to a gateway.

It can be seen that in the foregoing embodiment, optical signals ofdifferent RRUs are transmitted using different wavelengths, andcorrespondingly, optical transceivers of the cascaded RRUs work atdifferent wavelengths. Optical splitters are further provided, and theoptical transceivers of these cascaded RRUs are all connected to theoptical splitters, and are connected to a same optical fiber by theoptical splitters. In this way, the optical signals of the multiple RRUsthat are transmitted on the optical fiber can be transmitted to theoptical transceivers of all the RRUs using the optical splitters, andeach optical transceiver receives only a signal corresponding to its ownoperating wavelength. Therefore, each RRU can correctly receive its ownsignal, and when an RRU is faulty, operation of the other RRUs is notaffected. For example, when the first RRU is faulty, signals of theother RRUs can be directly transferred to the BBU using the opticalsplitters, and a signal of the BBU can also be transmitted to the otherRRUs using the optical splitters, thereby ensuring that the other RRUscan work normally, which resolves a technical problem of low systemreliability caused by that when an RRU of multiple cascaded RRUs isfaulty in an existing distributed base station architecture, all nextRRUs cannot work.

In addition, all links use different wavelengths for communication, andare completely independent of each other, which also resolves atechnical problem that when multiple RRUs are cascaded, a rate of anoptical transceiver increases and a quantity of cascaded RRUs on a samelink is limited because communication bandwidth is superimposed.

Embodiment 5

Based on a same inventive idea, this application further provides awireless radio frequency apparatus, where the wireless radio frequencyapparatus includes M RRUs, where M is an integer greater than or equalto 2, M optical transceivers, separately connected to the M RRUs, whereoperating wavelengths of the M optical transceivers are different fromeach other, and at least one optical splitter, where the at least oneoptical splitter connects the M optical transceivers to a same opticalfiber, that is, the M optical transceivers are connected to a sameoptical fiber by the at least one optical splitter.

Preferably, the optical splitter is a 1:N optical splitter, where N isan integer greater than or equal to 2 and less than or equal to M.

Preferably, the optical splitter is a 1:2 optical splitter, and aquantity of optical splitters is M−1.

Preferably, when M is greater than 2, the M−1 optical splitters areconnected to each other by a single-core optical fiber.

Preferably, the optical fiber is a single-core optical fiber.

Preferably, an operating wavelength of each optical transceiver of thefirst optical transceivers and the second optical transceivers includesa receive wavelength and a transmit wavelength.

It can be seen that in the embodiment, optical signals of different RRUsare transmitted using different wavelengths (which includes transmissionfrom an RRU to a BBU, and transmission from a BBU to an RRU), andcorrespondingly, optical transceivers of the cascaded RRUs work atdifferent wavelengths. Further, an optical splitter is further provided,and the optical transceivers of these cascaded RRUs are all connected tothe optical splitter, and are connected to a same optical fiber by theoptical splitter. In this way, optical signals of multiple RRUs that aretransmitted on the optical fiber can be transmitted to the opticaltransceivers of all the RRUs using the optical splitter, and eachoptical transceiver receives only a signal corresponding to its ownoperating wavelength. Therefore, each RRU can correctly receive its ownsignal, and when an RRU is faulty, operation of the other RRUs is notaffected, which greatly increases system reliability.

In addition, in some approaches, data of all RRUs needs to pass througha CPRI of the first RRU, and therefore, there is a relatively highrequirement on bandwidth of the CPRI, which increases costs, and in acase in which the bandwidth of the CPRI is limited, a quantity of levelsof cascaded RRUs is limited. In addition, an increase in the bandwidthof the CPRI increases a requirement on a rate of an optical transceiver,which further increases the costs.

However, after the foregoing solution is used, each RRU receives its ownsignal without the need to forward a signal of another RRU, whichreduces the requirement on the bandwidth of the CPRI and reduces thecosts, and does not cause any limitation to the quantity of levels ofcascaded RRUs. Further, each RRU no longer needs to be provided with twoCPRIs, thereby further reducing the costs. In addition, a decrease inthe requirement on the bandwidth of the CPRI further reduces therequirement on the rate of the optical transceiver, which furtherreduces the costs.

Although some preferred embodiments of the present application have beendescribed, persons skilled in the art can make changes and modificationsto these embodiments once they learn the basic inventive concept.Therefore, the following claims are intended to be construed as to coverthe preferred embodiments and all changes and modifications fallingwithin the scope of the present application.

Obviously, persons skilled in the art can make various modifications andvariations to the present application without departing from the spiritand scope of the present application. The present application isintended to cover these modifications and variations provided that theyfall within the scope of protection defined by the following claims andtheir equivalent technologies.

What is claimed is:
 1. A wireless radio frequency apparatus comprising:M remote radio units (RRUs), wherein M is an integer greater than orequal to 2; M optical transceivers, wherein each of the M opticaltransceivers is coupled to one of the M RRUs and uses a differentoperating wavelength set; and M−1 optical splitters coupling the Moptical transceivers to an optical fiber, wherein each optical splitteris a 1:2 optical splitter and is placed in a maintenance cavity of oneRRU, wherein each of the M optical transceivers is a single-corebidirectional optical transceiver, and wherein each operating wavelengthset comprises a transmit wavelength and a receive wavelength, which aredifferent and are respectively used to transmit and receive opticalsignals.
 2. The apparatus of claim 1, wherein the M−1 optical splittersare connected to each other by a single-core optical fiber when M isgreater than
 2. 3. The apparatus of claim 1, wherein the optical fiberis a single-core optical fiber.
 4. A wireless communications systemcomprising: a baseband processing unit; an optical multiplexer; M firstoptical transceivers coupled to the baseband processing unit and theoptical multiplexer, wherein each of the M first optical transceiversuses a different operating wavelength set, and wherein M is an integergreater than or equal to 2; and a wireless radio frequency apparatuscoupled to the optical multiplexer and comprising: M remote radio units(RRUs); M second optical transceivers, wherein each of the M secondoptical transceivers is coupled to one of the M RRUs, and uses adifferent operating wavelength set; and M−1 optical splitters couplingthe M second optical transceivers to an optical fiber, wherein eachoptical splitter is a 1:2 optical splitter and is placed in amaintenance cavity of one RRU, wherein the optical fiber is connected tothe optical multiplexer and one of the at least one optical splitter,wherein each of the M first optical transceivers and the M secondoptical transceivers is a single-core bidirectional optical transceiverand each of the M second optical transceivers corresponds to one of theM first optical transceivers, wherein each operating wavelength setcomprises a transmit wavelength and a receive wavelength, which aredifferent and are respectively used to transmit and receive opticalsignals, wherein a transmit wavelength of a first optical transceiver isthe same as a receive wavelength of a second optical transceiver thatcorresponds to the first optical transceiver, and wherein a receivewavelength of the first optical transceiver is the same as a transmitwavelength of the second optical transceiver that corresponds to thefirst optical transceiver.
 5. The wireless communications system ofclaim 4, wherein the M−1optical splitters are connected to each other bya single-core optical fiber when M is greater than
 2. 6. The wirelesscommunications system of claim 4, wherein the optical fiber is asingle-core optical fiber.